The present invention relates to marine structures having load bearing outer skins which are suitable to support a platform for carrying out operations in arctic and sub-arctic regions. Such marine structures are particularly well suited for conducting exploration and drilling in areas such as the Alaskan Beufort Sea and serve equally well for such operations as supporting production equipment, liquefaction plants, gas compression plants, crude oil storage and offshore loading facilities in this and other such regions.
Since in most arctic and sub-arctic locations, only about two months of acceptable weather for construction per year are available, structures employing a load bearing outer skin should ideally require a minimum amount of construction effort at the job site. Structures adapted for use in ice laden environments typically employ load bearing outer skins designed to safely resist substantial ice forces encountered when such structures are installed in an offshore location. Structures designed for offshore use in arctic environments have to withstand highly concentrated local loads from first year and multi-year ice features. Typical designs for load bearing outer skins of such structures include heavily reinforced or stiffened skin plate members for resisting local loads caused by ice formations. In the alternative, such load bearing outer skins may be formed from high strength, heavily reinforced and prestressed concrete or similar materials.
Since such offshore structures used in exploration in arctic areas must be relocated from one drilling site to another in the event a first drilling site proves unsuccessful, the overall structure needs to be light enough to be able to be floated from one location to the next with a very shallow draft.
Similarly, due to the short period available for construction in arctic or sub-arctic regions, construction techniques for building a load bearing outer skin must be simple, thereby permitting quick assembly.